Summary of Company's debt (Detail) (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Sep. 30, 2013	Dec. 31, 2012
Debt Instrument [Line Items]
Total debt	$ 87,434	$ 56,952
Current portion	(22,164)	(17,218)
Long-term debt, less current maturities	65,270	39,734
US Term Note
Debt Instrument [Line Items]
Interest Rate	2.50%
Total debt	25,813	29,312
Europe Term Note
Debt Instrument [Line Items]
Interest Rate	2.50%
Total debt	40,507	4,476
W.E.T. Term Note
Debt Instrument [Line Items]
Interest Rate	2.00%
Total debt	12,897	18,852
German Investment Corporation
Debt Instrument [Line Items]
Interest Rate	4.25%
Total debt	5,403
Capital Lease Obligations
Debt Instrument [Line Items]
Interest Rate	4.20%
Total debt	2,814	1,140
Bank of China
Debt Instrument [Line Items]
Total debt		$ 3,172